Does a rebuilt engine run warm until the break in is finished?

[themechanic]

1969 Coronet R/T. Factory AC car.

Classic Auto Air AC system.

Factory 054 radiator with a new 4 row copper core.

New 16lb radiator cap.

Factory 7-blade fan.

Factory shroud.

New Hayden short fan clutch

Green anti-freeze 50/50 mix.

New heater core.

FlowKooler water pump and 180° thermostat tested before installing.

Factory AC crank and water pump pulleys.

New hoses with spring in bottom hose.

New belts.

Penn Grade 30 weight break-in oil.

Engine has about 100 miles on it since a mild rebuild with a roller cam.

Starts, runs and drives perfectly.

Timing is 18 degrees base and 34 total.

Factory radiator, heater core and engine were all flushed out. (Some unknown person for unknown reasons put radiator stop leak in the cooling system. Trying to reach the shop for days but no answer. )

The car has a factory temperature gauge and an aftermarket electric gauge. The factory gauge stays about the middle. Running 200°F at a stoplight.

190°F on the highway with AC on.

Laser temp measurement in driveway was 215°F on the thermostat housing and around 200°F on both the upper and lower radiator hoses.

Just a degree or two difference between top and bottom hose.

Ambient is 92°F. Humidity is 37% and the heat index is 95°F.

 

[Cranky]

Sometimes....Do you have a big fan to put in front of it?

 

[themechanic]

Sometimes....Do you have a big fan to put in front of it?

This has a roller cam. So, just breaking in the piston rings by driving 500 miles.

 

[Kern Dog]

Run warm? Heck yeah it does. All those parts getting used to each other, the fitment is tighter than it was as a worn out engine. It is under no load so it is running leaner than it would out on the road too, this increases heat.
An engine that is broken in should be able to sit still and idle quite awhile before getting HOT but a fresh build can overheat a lot sooner.

 

[451Mopar]

Not much temp difference top to bottom? Automatic car? maybe use an external transmission cooler to pre-cool the transmission fluid before running through the radiator?

 

[R413]

Yes they run hot, your numbers look good for what you have there.

Also, thanks for all the detailed info. Many never post this stuff so we must guess.

If it's too warm then try a 160 thermostat. It will be fully open 20 degrees cooler.

Also you don't need a 50/50 mix antifreeze, that's -35 protectoion. What is the record winter low where you live? Less antifreeze cools better.

 

[Dennis H]

Yes, mine did.

 

[themechanic]

Not much temp difference top to bottom? Automatic car? maybe use an external transmission cooler to pre-cool the transmission fluid before running through the radiator?

Yes, automatic using transmission cooler in the radiator.

 

[themechanic]

Yes they run hot, your numbers look good for what you have there.

Also, thanks for all the detailed info. Many never post this stuff so we must guess.

If it's too warm then go,witha 160 thermostat. It will be fully. Open 20 degrees cooler.

Also you don't need 50/50 antifreeze, that's -35 protectoion. What's the record winter low where you live? Less antifreeze cools better.

Actually, they used 2 gallons of concentrate and filled the rest with water.

 

[Tony Tee]

Try a 160° thermostat if you want it to run a little cooler. Your 180°thermostat will start to open at 180°. ( just a suggestion.) I live in florida and put a 160° thermostat in my 2000 dakota. It was the best thing i ever did. I burned through 3 radiators due to the top plastic tanks were cracking from the heat. And when changing the oil. It would drain out like it was water. Now all that is fixed and i still own the dakota since new in 2000. 320k

 

[themechanic]

I wonder if there FlowKooler is flowing too fast nit allowing enough time for a thorough heat transfer. I may try swapping it for the 6 fin stock water pump for AC to match the factory AC pulley size.

According to Bouchillon Performance Engineering, the crank pulley is 7-7.5 inches in diameter and the water pump pulley is 5.875 inches for the proper drive ratio.

 

[themechanic]

Since the thermostat is easier I'll swap in a 160° before changing the water pump.

 

[Darter6]

Also, thanks for all the detailed info. Many never post this stuff so we must guess.

New Hayden short fan clutch

Amen to the first quote.
The fan clutch should be about 1 1/2'' from touching the radiator core. (Just a thought)
Also check the top of the radiator tank to the bottom temp. If the flow ( your thought on the coolant moving too fast) is correct you should see a drop in temperature at the bottom tank.
I agree with the rest of the gang that your numbers look normal.

 

[Don Frelier]

I think there is something wrong with your upper and lower hose readings being identical.
If they were you would have no cooling, which can't be the case as your numbers look pretty reasonable.

A couple other things:

1. Humidity and heat index only apply to humans not heat exchangers.
2. I wouldn't recommend running the AC during the break in phase.

Yes they do put out more heat until they are broken in.

 

[themechanic]

Amen to the first quote.
The fan clutch should be about 1 1/2'' from touching the radiator core. (Just a thought)
Also check the top of the radiator tank to the bottom temp. If the flow is correct you should see a drop in temperature at the bottom.
I agree with the rest of the gang that your numbers look normal.

There's barely any change in temperature between the top and bottom hoses.

 

[themechanic]

I think there is something wrong with your upper and lower hose readings being identical.
If they were you would have no cooling, which can't be the case as your numbers look pretty reasonable.

A couple other things:

1. Humidity and heat index only apply to humans not heat exchangers.
2. I wouldn't recommend running the AC during the break in phase.

Yes they do put out more heat until they are broken in.

I'm using a cheap Etekcity infrared thermometer.

I didn't turn the AC on until I got on the highway. Like, Dad always did. But I kept it blowing after I got off the highway a few blocks from home.

I'll probably just drive in the cool of the day for another 400 miles.

 

[Darter6]

There's barely any change in temperature between the top and bottom hoses.

The thermostat even if fully open should regulate the flow. We used to make a plate with a 5/8'' hole to slow the flow.Replacing the thermostat for test purposes to see the temperature differences.
As stated before the A/C factory pumps had different flow rates than non a/c. Maybe as you stated the new aftermarket pump is moving the coolant faster.
Just a thought

 

[Darter6]

I'll probably just drive in the cool of the day for another 400 miles.

 

[Bird 426]

Can't move the water too fast, doubt very much that it is the Flowkooler pump. Yes to possibly of other things.
When I broke in my aircraft engine, cycled wide open to 65 or 75% power till my oil temperature started to drop down to normal. Took roughly an hour.

 

[Kern Dog]

I wonder if there FlowKooler is flowing too fast nit allowing enough time for a thorough heat transfer.

This is a myth that seems to stay alive despite it making no sense.
Conversely, coolant that dwells in the radiator longer also allows coolant to dwell in the engine longer, increasing the heat transfer into the coolant.

Can't move the water too fast, doubt very much that it is the Flowkooler pump. Yes to possibly of other things.
When I broke in my aircraft engine, cycled wide open to 65 or 75% power till my oil temperature started to drop down to normal. Took roughly an hour.